Question: Simplify the following expression: $r = \dfrac{-3x - 8}{7x - 9} \div \dfrac{1}{5}$
Explanation: Dividing by a number is the same as multiplying by its inverse. $r = \dfrac{-3x - 8}{7x - 9} \times \dfrac{5}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $r = \dfrac{(-3x - 8) \times 5} {(7x - 9) \times 1}$ $r = \dfrac{-15x - 40}{7x - 9}$